Post #1843: Why are ceiling fans vastly more efficient than box fans?

 

In a nutshell?  To provide the same flow (CFM or cubic feet per minute), a small fan (like a box fan) has to move air a lot faster than a larger fan (like a ceiling fan).  And to move air fast, it takes disproportionately more pressure — and hence energy — than it takes to move it slowly.

The rest is just arithmetic.

I’m not talking slightly more efficient.  It’s well-established that ceiling fans are the most efficient type of home fan you can buy (reference).

I’m talking on-order-of five times as efficient as a box fan.  That, comparing the elderly ceiling fans in my house, against the most efficient modern box fan currently sold at Home Depot.

My main point is that the efficiency advantage of ceiling fans is rooted in basic physics.   It’s purely a consequence of their larger size.  It has nothing to do with (e.g.) the grilles on the box fan or the efficiency of various styles of electric motors.  It is simply that to achieve some given rate of air movement (cubic feet/minute), it takes far less energy to move a large volume, slowly, than to move a small volume, quickly.

Not only are ceiling fans more efficient than box fans, they always have been, and always will be.  It’s not the motor, or the housing, or the grille, or any of that.  It’s just physics.

Edit:  This also explains why bathroom fans are so slow at clearing the air.  If you wanted a bathroom fan that could move as much air as a box fan, it would require a 500 watt motor (Post #1859).

 

Continue reading Post #1843: Why are ceiling fans vastly more efficient than box fans?

Post #1841: Used electric vehicle prices are plummeting?

Caveat emptor.

It has been a long time since I last bought a used car. 

I have forgotten just how sleazy the low end of the used car market can be.

But I’m getting educated in a hurry.

Today’s lesson in low-end used cars?  A few weeks back, I was interested enough in an older Nissan Leaf that I scheduled an appointment with the dealer, to have a look at it.  Then I did my homework, and cancelled the appointment.

And, foolish me, I figured I at least owed the guy an explanation of why I wasn’t interested.  Because that’s what reasonable people do.

The ad for the car claimed excellent battery health, and a 110-mile range, per the independent estimate from Recurrent.com.  By contrast, once I learned to read the “gas gauge” of a Nissan Leaf, photos of the dashboard revealed barely 60 miles of range left, as well as a battery that was in mediocre health.  Via email, I told the dealer that’s why I was no longer interested.  The car really didn’t have adequate range left.

I continue to track the ad for that car, just to try to get a handle on the used car market.

In response to my explanation of that cancelled appointment, what do you think the used car dealer did to the ad for that car?

  1. Nothing.
  2. Removed the falsely inflated range estimate from Recurrent.com
  3. Removed the photos of the car that revealed the actual range.

If you guessed “c”, then you’re a lot less naive about the used car market than I am.  Or was.

As an economist, I really shouldn’t use the word “sleazy”, when the behavior is rational.  The dealer represents seller, plain and simple.  The dealer’s job is to get the best price for the seller, within some reasonable timeframe.  Anything that  increases the odds of selling the car, without getting thrown in jail, is fair game.  So, if fuzzying-up the information on range might help sell the car, then fuzzying should occur.  It’s up to the buyer to understand that and act accordingly.

In fairness, the dealer keeps dropping the price of that 2016 Nissan Leaf.  In any case, I’ve already made up my mind that I don’t want anything earlier than a 2018 Leaf, due to the rapid degradation of the battery in earlier model years of Leafs.

The lesson here is that it’s still a used car, even if its electric.  With everything that buying a used car entails.  Just because it’s eco-friendly doesn’t mean the dealer is friendly.  The upshot is that in trying to be a straight shooter, in a room full of crooks, all I did was help the crooks to be better crooks.


My local used EV market still appears too hot for my liking.

In addition to that 2016 Leaf, I have been tracking three 2018-or-later Leafs.  These have a different battery chemistry from older Leafs.  They retain their battery health and range much better than the pre-2018s and are priced accordingly.

Of the three cars I begin tracking less than two weeks ago, two have already sold.

Assuming that’s not just some kind of fluke, either I have an exceptional eye for a good deal, or the market for a reliable used EV is pretty hot.  At least around here. 


But the internet assures me that used EV prices are plummeting.

Official U.S. Consumer Price Index data are all-but-useless for judging long-term trends in the price of new and used cars.  I went through that in Post #1836.

Source: Bureau of Labor Statistics, via the Federal Reserve of St. Louis FRED system

The quality adjustment embedded in the CPI car price data mean that the price trends as published by the Bureau of Labor Statistics have nothing to do with how much money you’ll need to shell out to buy a basic car.  Such as Toyota Corolla, shown in yellow below.

But if car prices move fast enough, the actual change in prices will swamp the BLS quality adjustments.  And so, for sharp short-term price movements, the BLS data aren’t too bad.  From the BLS, we can see that used car prices peaked at the end of 2021, and have been mostly falling since.

Source:  Underlying data from the St. Louis Federal Reserve (FRED)

The BLS does not appear to publish any data separating electric vehicles from other types of vehicles.  So I have to turn to privately-produced price statistics if I want to get a handle on what’s happening to EV prices, as distinct from other types of vehicles.

And that’s where things turn a bit odd.  Because, as far as I can tell, a lot of private-sector price estimates show that the price of used EVs is plummeting.

Here are two such estimates, from what I believe to be independent data sources:

The devil is in the details.

The iSeeCars study is a study of used cars one to five years old.  And the measured price reduction in that segment was driven by Tesla’s decision to cut the price of its new cars.  More-or-less, what they measured is that the price of used Teslas fell about 30%.  In addition, it appears that they do not adjust for changes in the mix of vehicles sold, but simply take the change in the average asking price for a used EV.

The Recurrent study is also a study of used cars one to five years old.  It appears to be based on the simple average of the asking prices of seven common used EVs and PHEVs.  And, as with the iSeeCars study, a big chunk of the reduction is attributed to Tesla’s decision to cut the price of their new cars substantially.

That said, the Recurrent study shows a corresponding increase in (e.g.) the fraction of the used EV market offered for sale at less than $25K.  I’m pretty sure that excludes most Teslas.  The inference would be that these price declines affected the broader market, not just Tesla.


I’m still in no particular hurry to buy.

When all is said and done, my guess is that I should be in no hurry to buy a used EV.  Prices for relatively new models (one-to-five years old) appear to be falling, in large part due to new-car price cuts by market leader Tesla.  I don’t perceive that among low-end models, in my geographic area.  But its possible I simply tracked an unusual small sample of cars.

Although the price trends may be murky, one aspect is clear.  I’m still something of a babe in the woods when it comes to buying a used EV.  I need to get a lot smarter before I put my money down on a used car.  Even if it is an eco-friendly electric car.

Post #1837: Note to self: Get a 2018 or later Nissan Leaf

 

Edit 1/21/2024:  Between the time I wrote this, and January 2024, the price of used Chevy Bolts dropped so much that, in the end, I ended up buying a 2020 Chevy Bolt.  See Post #1924 for the reasoning behind that.

I continue to stumble across important facts about used EVs.

In this case, it’s that the 2018 (and later) Leaf is vastly better than earlier models.  That’s because Nissan finally scrapped its older, inferior battery chemistry that year.

Unsurprisingly, used Leaf prices seem to reflect that.

Continue reading Post #1837: Note to self: Get a 2018 or later Nissan Leaf

Post #1836: Will used-car prices continue to fall?

 

Warning:  This post contains economics.  It’s about the odd state of the used car market, right now.  And my guess that used car prices will continue to trend down from their December 2021 peak.

Update one year later, 7/26/2024:  At this point, the post-pandemic spike in used-car prices has pretty much run its course.  In real (inflation-adjusted) terms, used car prices are only slightly higher than they were before the pandemic.  Therefore, I’d guess that there’s not much potential for them to fall much further.

Here’s the updated graph, where I set the index of new and used car prices to a value of 1.0 in January 2020.  The underlying data are from the Bureau of Labor Statistics.

Original post follows.

 

 

Continue reading Post #1836: Will used-car prices continue to fall?

Post #1835: Buying an EV grocery-getter. Boiling it down to a Leaf.

 

Edit:  Between the time I wrote this, and the time I actually bought a car (January 2024), the price of a lightly-used Bolt had fallen so much that I bought a Bolt instead of a Leaf (Post #1924 ).

I’m trying to replace the gas vehicle I got rid of, about a year and a half ago, with an EV (electric vehicle).

Bottom line:  Well-used Nissan Leaf is the best fit, for my needs. Continue reading Post #1835: Buying an EV grocery-getter. Boiling it down to a Leaf.

Post #1834: EV market, the missing middle: Used $10K to $20K

 

So far, I’ve looked at the bottom end of the used EV market (under $10K).  I’ve looked at the bottom end of the new EV market (under $51K).  The leading candidate for my EV purchase seems to be the Chevy Bolt.  New, those have a ridiculous markup.  Used, they seem to fall in line with competitors’ prices.

This post looks at the used EV market $10K to $20K.

Upshot:  Nothing to see here.  Or, at least, nothing new and actionable, for me.    In this post, I skim over this used EV segment and more-or-less dismiss what I find, relative to a new or lightly used Bolt.


In this segment of the market, I see …

  • Nissan Leaf, later model years, higher original range.
  • Chevy Bolt, earlier model years, not much discount compared to 2021.
  • The occasional Ford, Fiat, Hyundai, Kia, Mercedes, Mitsubishi
  • And the VW e-Golf.

The Leaf, of that generation (say 2016-2020 or so), not a bad car.  You can get them with original EPA range around 150, I think.  But the more I look at it, the more the basic design of the Leaf just has issues.  Between the lack of battery cooling and the obsolete fast-charge socket, it really seems that it never was intended to be anything but an around-town car.

Nothing wrong with it, but given what’s available, nothing that makes it stand out as a must-have.  Particularly as Virginia is hot in the summertime, and these vehicles have a hard time charging in the heat.

The Chevy Bolt is the leader so far.  You don’t seem to get a huge discount by rolling back to (say) a 2017 or 2018 model year.  So I don’t see these older Bolts as standing out, relative to a new-ish Bolt.

There are some stray other makes and models.  I just don’t feel like it’s worth the effort to research each one.  Do I really want to own one of the 100 Kia Soul EVs sold in this area, six years ago?

The there’s the VW e-Golf.  The e-Golf deserves a closer look, because those are available in large numbers as used cars in this price range.

Unfortunately,

  • The earlier model years had just 83miles EPA range
  • The 2017 and later, with 125 miles EPA range, cost $19 and up.

Absent some way to know that these are phenomenal cars, I don’t much see the point of looking at them further.  I don’t want the ones with short original range, and the ones with longer original EPA range cost about as much as a used Bolt.

To sum it up, there’s really nothing here that jumps up and says “buy me”, to me.  New Bolt for $26K net of tax credit, used low-mileage Bolt for $16 net of tax credit, for me, those seem to dominate.


What about used PHEVs?

PHEVs (plug-in hybrid electric vehicles) are hard to search for, for a variety of reasons.

One, they fall through the cracks.  They aren’t EVs, but the health of the traction battery matters greatly, like EVs.  Unlike EVs, most manufacturers offer absolutely no guarantee on the electrical range.  There’s absolutely zero indication about the state of health of the battery, in ads for PHEVs.

Two, these also have internal combustion engines, with all the complications that implies, for buying a used car.

Three, Edmunds apparently does not maintain PHEVs as a separate category of cars.  So I have to search for individual models.

Typical asking prices in this area:

  • Volt, 2018 or so, 40K miles, $25K
  • Prius Prime, 2018, 100K miles, $20K
  • Kia Niro, 2018, 40K miles, $26K

There are some larger SUVs that were not of interest to me.  Those mostly seemed to be at $30K and up.

I’m not sure how to proceed in this segment, as I have no way yet to assess the state of the battery in these cars, short of showing up and driving them.

Post #1833: Used EV rethink


I’m about a week into trying to buy a used EV.  I’m typically working from the listings provided by Edmunds.com, for a 25-mile radius around my ZIP code, here in Vienna VA.

It has been an education. 

Good news is, I haven’t spent any money yet.  Bad news is, I’m not sure I’m any closer to getting a used EV.

Maybe a change of focus is in order.

As of this last round, my best candidate is a two-year-old Chevy Bolt, with 20K miles on it, for a net $16K. 

 


First stop:  Used EVs, $10K and under.  What did I learn?

1:  The Leaf dominates this market segment.  By that I mean, most of the vehicles for sale are used Leafs, 2011-2016 models.  Never saw a 2017 listed.  And, on paper, the Leaf SV has better specs than the common alternatives in this market segment (Chevy Spark, Smart for Two, and Ford Focus).

2:  A used Leaf will tell you how much range it has lost, right on the “gas gauge”.   The same gauge will give you a snapshot of the range, subject to a lot of random variation.  But the bottom line is that if the seller posted a picture of the dash, showing that gauge, you can immediately weed out the ones with a lot of range loss.  I went through this in detail in recent posts on this topic.

3:  That’s handy, because the “Recharge.com” estimates of battery range provided in used car ads can be wildly inaccurate.  I got interested in a car because it had a Recharge.com range of about 110 miles.  Until I saw a picture of the dashboard, and found that the actual range was closer to 60 miles.

4: There’s a real “market for lemons” aspect to the used EV market.   By that I mean that used Leafs offered for sale around here had experienced an average of 8 percent per year range loss.  That’s about twice the typical range loss for this make/model/age.

Not that the used gas car market doesn’t suffer from the same thing.  But here, you can quantify the degree of adverse selection with a single, objective number.

Two things brought my search in this market area to a screeching halt.

5:  The best range I could find, on a used Leaf in that market segment, was 60-ish miles.  And upon reflection, that doesn’t really cut it if you want an all-season, all-Metro-area car, that will last you some years.  Highway travel reduces range.  Cold (and for the Leaf) warm temperatures reduce range.  The Leaf uses an obsolete CHAdeMO fast-charging plug that will become increasingly hard to find as time passes.  And that range is going to continue to degrade.

I could  see myself owning a car that I would hesitate to take half-way around the DC beltway, in the winter.  At which point, it’s no longer a fully-functional car, and has started the slow slide to becoming a glorified neighborhood electric vehicle.

6:  But the biggest problem is that some Leafs get temperamental as they age.  After reading enough accounts, it’s pretty clear that some well-used Leafs  can no longer deal with high-power/high-current-flow events, such as highway speeds, long uphills, or regenerative braking.  For those, you have to “baby” the vehicle, and otherwise live within its limitations.  Understand, this is for a car in excellent repair.  It’s not something that’s fixable, short of replacing the battery pack.

In hindsight, I see hints that other used EVs suffer from the same current-limiting issue as they age.  I suspect the extreme examples I found in older Leafs are due to the small battery pack.  Cars with larger initial range (e.g., Tesla) seem to manifest the same issue as a pronounced “loss of oomph”, rather than a car that will shut down if you push it too hard.

 


A new focus:  New EV under $30K?

Near as I can tell, in this market segment, by MSRP, you’ve got the Chevy Bolt, and the Nissan Leaf.  Both cars are about the same size, and both cars are about the size and weight of a Prius Prime.  So I suspect I’d be comfortable driving either one.

Source:  Fueleconomy.gov

Of these, on paper, the Chevy Bolt appears to be a much better choice.  First, the Bolt has a much higher range (~260 miles) than the Nissan Leaf in this price range (~150 miles).  (You can get a Leaf with more range, but it costs another $8K or so.)  Second, the Bolt has the modern CCS fast-charging socket, while the Leaf retains the obsolete CHAdeMO plug.  Third, the Bolt has (I think) a battery temperature management system, while the Leaf (I think) remains passively cooled (which a certain E. Musk described, circa 2010, as “crude”).

All together, this makes the 150-mile Leaf close to unusable for long-distance driving, certainly in summer.  Charging heats the battery.  The car responds by slowing the rate of charge.  Apparently, a mid-summer highway trip in a Leaf is just an excruciating experience.  This, per a YouTube presentation of a West Virginia Leaf owner who filmed his three-day trip from West Virginia to Florida.

Whereas the Bolt, in theory, would get me from Vienna VA to (e.g.) Ocean City Maryland (174 miles) without a recharge.  Not possible in the Leaf.  Per the diagram below, the Leaf’s one-way range limit is just slightly larger than the Bolt’s round-trip range limit.

There are other functional differences.  For example, the Bolt only has resistance electric heating, not the more-efficient heat pump that can be had on the Leaf.

But the Bolt has two big problems.

Fire.

The first problem with the Bolt is its checkered history.  GM ended up recalling every Bolt ever made, 2017-2022. 

There were … not battery fires, per se, but fires in the high-voltage battery compartment.   (A lithium-ion battery fire is all-but-impossible to put out.  Once that starts to burn, the car (and whatever the car is parked in) is toast.  These were events that charred some of the interior, so, for sure, it wasn’t the Li-ion battery that outright caught fire.  But the batter was the source of the heat that charred the battery compartment.)

Per the NHTSA, there were two fires out of a population of 78,000 cars, up to 2020.  Three more such fires occurred after 2020, out of a larger population of vehicles.  In the end, GM recalled all of those (2017 to 2022).

Reading further across several sources, the problem arose in cars with bad battery modules, where the owners charged the car to 100%.  GM’s interim guidance was, in effect, don’t do that.  Don’t charge to 100% (and don’t run the battery down to zero).  Initially, GM agreed to replace all of those batteries, then they backtracked, and offered a software fix to monitor for the presence of those defective modules.  Basically, they modified the software so that the car’s software would raise a red flag if that car had one of the “bad” batteries.

FWIW, the used-car market appears unconcerned, as those Bolts sell on a par with the lower-range Leafs.  Here’s my crude summary, below.  With either car, accounting for the different tax credits for new and used cars, buying a two-year-old Bolt or a two-year-old Leaf would only save about $4500 off the new car MSRP.  (But see below, there are no Bolts available new MSRP).

FWIW, there appears to have been has only been one known Leaf battery fire in the U.S. in the entire history of the car.

That said, I’m not too concerned about the fire risk.  First, I avoid charging Li-ion batteries to 100%, because it shortens their life.  Two, this will be housed on an ancient detached garage, so if it burns, it’s not going to take my house with it.

Bolt:  Unobtainium near MSRP

Just to be sure I’m not hallucinating, this is what Chevy says:

Near as I can tell, those prices are a complete fiction.  At least in this area.

I don’t know whether my local Chevy dealers have figured out a way to collude on prices or not, but every one, in my area, has chosen to mark the up the Bolt by roughly the same amount, about $6000 over MSRP.

What a coincidence.

There’s one dealer within 250 miles that claims to have one, at a more reasonable markup over MSRP.  But upon investigation, that’s vaporware.  They’ve ordered one from Chevy and are pre-advertising it.

There’s a second dealer that claims to offer some at just over MSRP.  But upon inspection, that’s the price after you’ve paid them roughly a $5000 down-payment.

In short, the lowest actual asking price for the base-model Bolt, that I have run across, within a roughly 500-mile radius of my home, is about $33K.  Which translates to $25,500 after Federal tax credit.  Plus the usual fees, taxes, and so on.

The rest of the low-end new market.

To put a cap on it, per Tesla, today, the cheapest model available in my area is a Model 3 for $51K, with a range of just over 300 miles.

To put a floor on it, based on the cheapest hybrid:  A new Toyota Corolla hybrid gets 50 MPG (per EPA) and can be had around here for $25K asking price.  Buying that car, instead of an EV, would add about 0.4 tons C02 to my annual carbon footprint, assuming 3000 miles a year, and assuming Virginia’s electrical generation averages 0.65 pounds C02/KWH.  Around here, a new Toyota Prius looks like it’s almost unobtainable for anything near MSRP.  I’d probably be looking at $36K to buy a new Prius in this area.  At the very bottom end of new-car prices, a new Nissan Versa can be hand for $18K, and gets about 35 MPG.

What is the middle door for?  Only she knows.

Lightly used EV?  Leaf is a poor value.  Used Bolt avoids the current new-car-dealer surcharge.

For the Leaf S, if I were willing to roll the dice on a two-year-old used car with 20K miles, I could save a whopping $4.5K.  That small savings is due in part to the different tax credits for new ($7500) and used (up to $4000) cars.

For the Bolt, the used market appears to avoid the current high dealer markups on new Bolts.  There, under the same conditions (two years old, maybe 20K miles), I would save more like $10K, relative to actual current new Bolt asking prices.  I don’t know whether that reflects the fact that these cars were recalled.  But as far as I know, the 2023 is no different from the 2021, it’s just that GM installed the new software from the get-go.


To summarize

I’m making progress.  I think.

Looks like a new or lightly used Chevy Bolt is the sweet spot, so far, for me.

There’s probably nothing in the $10K-and-under used EV market that I want.  All the cars in that segment started out with small battery packs.  I believe that, as the car ages, those small batteries make the car sensitive to even a few weak battery modules.  There’s too high a chance that now, or in a few years, I’ll end up with a temperamental vehicle that can’t be trusted to do normal all-around driving.

The only new EV available for under $30K asking price, around here, is the Nissan Leaf S.  That has some known drawbacks (no battery cooling, obsolete fast-charging port), and apparently is really not practical for any sort of summertime road trip, due to the extreme charge times with a hot battery.

A Chevy Bolt, with the current ridiculous dealer markup, but after the Federal tax credit, costs about the same as the cheapest new hybrid cars.   For example, it’s about the same as the base model Toyota Corolla, which gets 50 MPG EPA.  So, in the sense of avoiding carbon footprint, it costs me nothing to choose the Bolt over a new hybrid.

(Not shown, there’s also the Ford Maverick hybrid truck which would, in theory, cost about that much.  But those are also more-or-less unobtainable at reasonable markup in my area.  Those get 37 MPG, and have all the the functionality of a pickup truck.)

Cheaper than that, and the only available new cars are non-hybrids, with what appears to be a maximum gas mileage of around 35 MPG.  Of which the Nissan Versa is an example.  But now, still in the early stages of our global warming disaster, I’d say that the last thing I want to do is cause yet another straight-gas car to be created. 

The upshot is that if I refuse to buy anything less efficient that a hybrid, I might as well get a Bolt EV.  With the tax credit, the Bolt costs about the same as the cheapest hybrid.

And then, the question is whether I want to save maybe $10K by gambling on a two-year-old used Bolt.

Go up another $10K to $15K, and you have your choice of new EVs.  But just as a matter of taste, I find none of them to be any more appealing than the Bolt.  Some are modestly larger.  Some have (I guess) more prestigious names than Chevy.  None materially exceeds the range of the bolt, until you hit the $50K bottom-end Tesla.

Das Bolt von Barbie, only available in Germany.

The Bolt is a risk, due to a history of rare battery overheating during full charge.  In theory, GM addressed that.  In practice, you aren’t going to know for sure.  Certainly, the market has not shied away from the Bolt.  Even used Bolts are pretty fully-priced.  And I don’t think GM fixed the issue at any basic level, they just installed the newer software on the new Bolts at the factory.